Wisconsin OWI Blood Test

In Wisconsin, it's illegal to drive a motor vehicle with a blood alcohol content (BAC) of .08% or higher (the limit is lower for commercial vehicle operators and underage drivers—.04% and .00%, respectively). There are several ways to measure BAC; while breathalyzer tests are the most common, blood tests can also be used to determine if a driver is over the legal limit.

Administering a Blood Test

Unlike a breathalyzer test, which can be administered by an officer at the police station, a blood test is considered a medical procedure and must be conducted by an approved healthcare professional in a clinical setting. There are also a number of regulations that must be followed in order to maintain the integrity of the blood sample. Failure to follow the proper guidelines while collecting, storing, or transporting the sample could cause your BAC reading to be thrown out.

Once the sample has been drawn, it's sent off for testing. The instrument used to analyze alcohol in the blood sample is known as a gas chromatograph. This device separates the compounds and extracts the alcohol in order to measure BAC.

Potential Blood Test Defenses

While the blood test is the most accurate of all the BAC tests, there are a still a number of defenses that can be used to challenge your reading. For example, if an alcohol-based solution was used to clean your skin before the blood draw, the results of your test may be greatly inflated.

In addition, the chain of custody for the blood sample must be properly documented. If just one link in this chain is unaccounted for, this is enough to have the entire blood test thrown out.

Call Our Law Office for Advice

As a dedicated OWI defense firm, Tracey Wood & Associates has access to the top expert witnesses in the area of blood testing. Our attorneys understand that blood tests are subject to errors, and aren't content to accept your reading at face value.